Electronic devices require an input unit to input or control information. In the case of computers, a mouse and a keyboard are most widely used as the input unit. Further, in the case of laptop computers or netbooks, a touch pad is used as the input unit. In the case of recently developed digital televisions, a remote controller is used as the input unit. Smart phones or smart pads such as iPad or Galaxy Tab use a touch pad or a touch screen as the input unit. The mouse enables anyone to easily input desired information, but has several limitations.
The mouse is classified into a mechanical type, an optical type, and an opto-mechanical type. The mechanical mouse is designed to detect movement of a ball located at a lower end thereof and move a pointer in response to the movement. The optical mouse is designed to detect movement on an underlying grid pad on the basis on a change in grid detected by a photosensor located at a lower end thereof, and move a pointer in response to the movement. The opto-mechanical is designed to detect movement of a disk with slits using photosensors, and move a pointer in response to the movement.
Such conventional mice employ a method in which the mouse is moved by a user, and detects the movement to move the pointer in response to the movement. As such, to move the pointer using the mouse, a space which the mouse can move is essentially required.